This is how I equip my Vulture for RES hunting.http://www.edshipyard.com/#/L=60N,4zh7Px3we0_g0mI0mI,316Q8I6Q5K7_6u5A,7Sk15O12G10i10i
The gimballed beam will handle anything smaller than a Clipper on its own, so the cannon is just used for power plant takedowns of Clippers, Dubsteps, Pythons and Anacondas. (Actually, the gimballed beam on its own will quite happily rip up any NPC - it's just quicker to take down Anacondas if you have the cannon as well!)
In the right RES, this spec will make you 2MCr an hour, no problem. I'm usually quite conservative with my cannon use (that is, I only fire it if I know I'm going to hit the power plant), so I usually have about 90 minutes between reloads, which is about as much as my attention span can take in a RES or combat zone.